Concerned with software or hardware firewalls

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1k views

I'm using a Cisco ASA as a VPN endpoint. Where do the VPN clients get firewalled?

(Is this too application specific? It seems like a reasonable question that would be useful to other people...) So, I've got this ASA in front of a network that I didn't set up. It's been ...
3
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1answer
66 views

How does firewall differentiate between browsing and downloading?

The firewall installed at my college's router allows me to surf the internet but never allows me to download any package that has a size more than 100mb. I wonder how exactly does it differentiate ...
3
votes
1answer
30 views

Why can't nmap identify the danted(socks5) service on non-standard port?

I'm testing nmap's abilities, I started a socks5 proxy server with danted, and started it on port 10090 I tried the following command, and expect it to tell me port 10090 runs a socks server, nmap ...
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3answers
642 views

Suspicious VMware connections that bypass firewall

I'm running VMware 5 and I have found that when I start up VMware I see two connections: TCP 10.100.100.161:55555->as-40816.engx.vmware.com:https (ESTABLISHED) TCP 10.100.100.161:55556->a184-85-...
3
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1answer
144 views

Who watches the watchmen? User empowerment over firewall behaviour on a personal computer

I've been exploring the gamut of free Windows firewall applications recently and have encountered the following problem: The better firewalls are excellent at stopping other apps from phoning home ...
3
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3answers
404 views

Security issues in a Dotnet Web application

I was required to fix three low risk security issues of a Web Application on a Windows 2003 server, NetFramework 2.0, IIS/6.0. It is tracert-able. That may assist for crackers to know network ...
3
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2answers
310 views

Can ipopts be used to circumvent a pf or iptables firewall source IP based blocking?

Can one use ipopts, and in particular IP source routing, to circumvent source-based blocking in pf or iptables? For example, with OpenBSD's pf: block in all # default deny block out all pass in on ...
3
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1answer
62 views

If a firewall deletes DOS packets before they reach the designated application. Is it then possible to break trough the firewall with a DDOS attack?

My Question is that if a Firewall blocks for example a DOS attack of UDP packets. Is it then possible to "break" or take up the capacity of a server by sending enough packets trough a DDOS attack? or ...
3
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1answer
54 views

Firewall - Allow WMI internal network

I am not totally sure if this is the correct stackexchange to place this question, so just let me know if it should be somewhere else. I am looking into IT asset management systems and for these ...
3
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2answers
146 views

Should I block outbound TCP RST (on closed ports)?

I have a range of inbound TCP ports open on the firewall, but usually closed on the host machine. I see a handful of unknown connection attempts each day, for which the server returns TCP RST. I ...
3
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1answer
148 views

Are Keystroke and Click Loggers Legal? [closed]

I worked with the firewall "Nobero" which is paid and bit expensive. It is a complete Network Firewall including groups policy, banning URLs and social sites. But It has a feature of tracking users' ...
3
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1answer
122 views

IPsec: Is AH in tunnel mode secure?

I have a site-to-site IPsec VPN which was performing poorly (10 -20% upload/download speeds as a percentage of available WAN circuit bandwidth) when using ESP in tunnel mode with DES encryption and ...
3
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1answer
151 views

Tracking down the source of email attacks

For the past week our company's IDS has been blocking 100-200 meeting invite emails per day from a specific client that are loaded with buffer overflows targeted at Exchange 2003. The payloads are ...
3
votes
1answer
771 views

Limit BitTorrent Sync connections to a specific network

Is it possible to limit BitTorrent Sync connections to a a specific network using the client software? Right now the closest I can come up with would be IP limitations imposed on each client using a ...
3
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3answers
9k views

Config Server Firewall: What Outgoing ports need to be open for wget and apt-get install?

I am just configuring CSF and I have to specify my outbound ports here. I am trying to close as many as possible leaving only what I need open, however what do I need to leave open for wget? # Allow ...
3
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1answer
2k views

How can I find the process that is trying to use smtp to send email?

Previously I asked Who (which process) is calling curl? and I got very good answers (this answer in particular) which basically replace the curl binary with a shell script that logs each call to curl ...
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1answer
5k views

Is opening both TCP/UDP less secured than just TCP or UDP when needed and why?

If application needs opened port X UDP, or X TCP combination. Is there any potential risk by opening both UDP/TCP as I usually am not sure which one the application uses?
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2answers
80 views

Why does our network firewall drop netbios-ns packets?

In our local domain environment, we use Sophos UTM to protect our network. When I check the firewall logs, I can see that a huge number of packets dropped by the firewall are netbios-ns (UDP 137) ...
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2answers
204 views

Firewall UDP Packet Source Port 53 Ruleset Bypass

I have a question regarding recent PCI DSS scan performed on our network. On some of the Windows 2008 servers (physical and VM), there is a risk found "Firewall UDP Packet Source Port 53 Ruleset ...
3
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1answer
678 views

Is it possible to force client use TCP instead UDP for DNS queries?

Assume I am managing a firewall between DNS server and clients. Is there any way to force clients use TCP rather than UDP, so we can prevent DNS spoof types of DDoS attacks?
3
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1answer
190 views

Security of OpenVPN against sophisticated DPI solution

I'm planing to build a device (prototype) that act as a portable security gateway. To make this, I choosed OpenWRT running on Raspberry Pi with OpenVPN for VPN connection. My main purpose of this ...
3
votes
3answers
210 views

Segregating a Printer in my Enterprise Network

I have a EAP-TLS network at home which I've managed for some time now. I just got a new Brother HL-5470 printer so I can finally print things at home, which is really nice. The only problem is that ...
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4answers
116 views

Do I need antivirus for this unusual installation - or just firewall?

I'm donating an old Windows XP laptop to a school. The machine will spend its golden years doing only one thing - a process that consists of just three steps: Recording lectures and discussions ...
3
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1answer
3k views

Expose web service in a secure manner

Requirement I have a web service I need to expose on the DMZ for external communication. The web service communicates directly with a critical database that sits on an internal net. Current ...
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5answers
189 views

Windows: Any method to enforce user confirmation before the browser opens a URL requested by an external desktop app?

A robust outgoing firewall will protect against desktop applications directly connecting to the internet without your permission. However, as the browser is a generally authorized application for ...
3
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1answer
1k views

Isolate a Virtualbox VM from local network [closed]

I have the need to isolate a virtual machine created with Virtualbox from the local network but I need to provide internet access to that machine. It is the first time that I face this kind of problem,...
3
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1answer
123 views

SYN scan, determining scan vs large file upload

In a system attempting to detect SYN scans, one technique is to analyze the rate of change of (network packets sent from victim host per second). Processes such as uploading a large file would not be "...
3
votes
1answer
539 views

SSL VPN placement strategies

I wanted to know the advantages and disadvantages of placing an SSL VPN with respect to CIA in different locations: with firewall within the internal network within the DMZ Any reference also ...
3
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1answer
301 views

Why strip accept-encoding?

It seems that there are multiple "security" products which strip or mangle 'Accept-encoding' headers, thus forcing non-compressed responses from HTTP servers. I've been trying to imagine if there's ...
3
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2answers
617 views

1 PIX firewall, 2 routers, 2 switches. Please answer a couple questions about hack lab

I bought a bunch of cisco equipment for a project and I got 1 PIX firewall 2 switches and 2 routers This is my plan for a topology but I am new at this so I need help. I am basing this off the ...
3
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1answer
43 views

Better alternative to WAF path whitelisting?

We are managing a WAF which is being used by some applications. Recently I tried to use a Valid URL module to white list all the APIs and static resources of an application. Although from the security ...
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2answers
103 views

How to restrict access to the internet for some computers on the network?

I’d like to differentiate machines (or, possibly, users) on my small business network so that only some of them have access to the internet. The solution I’ve been using to this day is quite terrible: ...
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2answers
339 views

how can an attacker access a system through a compromised router?

Let's say an attacker gained access to the admin panel of a home router with port 21, 23 and 80 open. I mean the attacker has full control over the router, thus being able to port forward, etc... ...
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2answers
133 views

When should I drop a packet with ICMP type 3, code 9 or 10, TCP RST, or TCP ACK?

This answer says there are a few ways of dealing with a blocked packet at a firewall: At each of these levels a 1st IP packet (and any other protocol packet as an ESP or AH packet) might receive ...
3
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1answer
150 views

Can NATs and firewalls blacklist IPs when trying to UDP hole punch?

I am developing a P2P application that will make use of UDP hole punch to connect two peers behind NAT. When dealing with connections between a cone and a symmetric, unpredictable NATs, however, hole ...
3
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2answers
4k views

Blocking incoming traffic from privileged port (< 1024) to mitigate DNS DDos Amplification attacks

Hope someone can clarify. As I understand, in a DNS DDos Amplification attacks Multiple DNS queries are sent to a vulnerable name server with the source IP spoofed to that of the target server. The ...
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5answers
445 views

Enforcing personal firewall for OS X

We're currently doing PCI compliance, and one of the requirements is that mobile devices that have access to systems involved in processing card data have personal firewall software installed which ...
3
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1answer
1k views

HTTPS form submissions are blocked on corporate networks

We have an HTML form which is submitted via HTTPS. We've noticed that when the form is submitted on a home network, it seems to go through just fine. However, when the form is submitted on certain ...
3
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1answer
2k views

w00tw00t.at.ISC.SANS.DFind iptables fix - abusable?

It's only an idea. I've recently logged that my server is scanned by w00tw00t tools. I found many solutions to this, such as use of apache mod-security, fail2ban, etc.. The one I want to speak about,...
3
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1answer
909 views

Mac sending hundreds of packets to gateway

I've got a user on my work network who brings her personal laptop (macbook) in for work. They've been having some horrendously slow network issues on everything past that hub, so I did some packet ...
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0answers
94 views

Modifying shell code to bypass Windows Firewall

As part of my OSCP's training, I'm supposed to get a shell on a Win7 machine using browser's exploit (MS12-037) with Windows firewall on. I have an idea but I'm having hard time applying it. What I'...
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0answers
75 views

I'm looking for a decent book on network and infrastructure security [closed]

I'm currently looking for a decent book on network and infrastructure security (especially in the enterprise context). Could you point me to one or two recent books, please? Thanks a lot in advance! ...
3
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0answers
263 views

Firewall in virtual machine

I'm putting my server to use as a file server and a firewall. I'm looking at KVM or Xen VM setup where file server and firewall get their own VMs and host is just supplying the hardware (so Xen way, I ...
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0answers
1k views

cisco asa syn flood detection and response not working

I have a Cisco ASA 5510 (ASA Version 8.3(2)) that has been getting a syn flood attack on it (or more accurately through it - targeting a host behind it) a couple of times a day for the past few days. ...
3
votes
2answers
215 views

How common is port-knocking? [closed]

Today I read about port-knocking for the first time. It has been a pretty known concept for more than ten years, but I don't know anybody who uses it for their servers. How common is the usage of ...
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4answers
45k views

What is the difference between antivirus and firewalls

I need a brief explanation about the differences between antiviruses and firewalls
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5answers
664 views

How do a firewall's rules for individual programs work?

I kind of know that how a firewall's rules for IP/port work, but I have no idea how a firewall deals with individual programs. In other words, how does the firewall know a program wants to access the ...
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6answers
2k views

How do I prevent data from leaving my network?

I have a network of about 10 computers and I want to prevent sensitive data and source code leaks. To achieve that, I would like to block all file uploading / attaching. What are the options ...
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3answers
10k views

What, specifically, does the Windows Firewall do?

My understanding of the situation is that, when the Windows firewall is off, every port on the computer (all 65535 of them) is fully open. This means that any application running on the computer can ...
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3answers
2k views

How to block the websites on client machines

In our office we are blocking sites like Facebook, Twitter etc.The problem is that some of the users bypass our proxy and firewalls through external proxy sites like www.youhide.com or www....